An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot aboard. The size of drones may range from small hobby scale suitable for close range operation proximate to a user to large scale systems capable of hauling large payloads over many miles. Drones used for depth mapping are typically very large and commercial grade. Smaller drones may not produce sufficiently detailed images that are typically required for mapping.
Current drone based solutions put two cameras on a single drone in a rigid stiffener to ensure that the relative positions of the two cameras do not change after initial calibration. However, the size of the rigid stiffener is often limited to the size of the drone (with larger drones being more expensive). These current stereo solutions either need a very large (and thus expensive) drone or must compromise on accuracy.
Other efforts at depth mapping rely on Light Detection and Ranging (LIDAR), which operates using time-of-flight, but requires high powered, bulky, and expensive drones that have very poor spatial resolution (x-y) and orders of magnitude less dense point clouds than the dual camera solution. In other systems, Structure-from-Motion (SfM) uses a single color camera and take pictures at multiple times at different locations to create synthetic longer baselines (virtual stereo pairs), but are very dependent on accurate visual (and inertial) odometry to track the drone's own location. These systems also require that the scene being imaged does not change. SfM also requires capturing data and post-processing it, which is not conducive to real-time imaging.